It is well known that rotary snowplows are motor-driven vehicles equipped at their front ends with one or more rotary plows. The snowplows progressively plow a snow blanket or snow piles while centrifugal action dumps the plowed snow on both sides of a snow track.
The front part of these plows or blades is unprotected in order to clear snow. This exposure constitutes a genuine hazard for people since accidental contact with exposed rotating blades can cause serious injury, such as dismemberment or crushed limbs.
This risk might be obviated by proper protection devices that are adjustable in height according to snow level. However, such protection devices would not be very efficient.
It should be observed that the blades are very heavy and rotate at a rather high speed during operation. Hence, the blades have an extremely high inertia. Even if an operator were aware of an accidental contact and would shut off the snowplow, the blades would continue to rotate for several seconds, thus causing serious injury.